The present invention relates to peristaltic infusion pumps for pumping of medical fluids and the like to and from a patient, and more particularly to a peristaltic infusion pump system which reduces the likelihood of incorrect connection and use between the system and a patient.
Peristaltic pumps of the type known for use for the infusion of medical fluids, or for the removal of body fluids from a patient, are generally characterized by use of a length of flexible tubing which is disposed within a compression chamber formed by a compression surface and a rotor assembly. The rotor assembly is typically provided with a Plurality of parallel axis rollers disposed about the periphery of a wheel-like rotor. Upon rotation of the rotor assembly, the rollers are biased against the tube which is supported by the compression surface, and the rollers successively pinch-off the tube and advance the location of the pinch-off so as to progressively advance the fluid within the tube at a rate in part determined by the angular acceleration and angular rate of rotation of the rotor. The pump rate is also determined by the viscosity of the fluid material, characteristics of the tubing through which the fluid flows, tube length and the inner and outer diameters of the tube through which the fluid flows. It is known to provide cassettes which facilitate the insertion and removal of such lengths of tubing into and out of the infusion pump. With such cassettes, typically, the user removes the cassette from the pump, and then positions the tube into the cassette (or within the housing of the pump) and then returns the cassette to the operating position. In some prior art configurations, the cassette includes the compression surface rigidly affixed to the cassette.
One danger of the prior art devices occurs because there is often a choice of tubes (of varying inner and outer diameters and other characteristics) which might be used so that a desired flow rate may be achieved. In such cases, operation error (in the selection of the tube) may lead to selection of the wrong diameter tube for the desired flow rate. Also in some cases, the direction of flow through the tube is important and it is possible for a user to install a tube backward, leading to deleterious results.
It is important to provide a peristaltic infusion pump in which fluid flow rate and fluid flow direction can be easily and accurately controlled. While present microprocessor and motor technologies enable provision of an intelligently controlled fluid pump, still prevention of user error is not guaranteed.
It is an object of the present invention to provide a peristaltic infusion pump system which reduces the likelihood of incorrect user hook-up and direction of operation.
It is another object of the present invention to provide a keyed removable cassette and a mutually keyed disposable tube set which dictates the direction of fluid flow and flow rate when utilized with a mutually keyed peristaltic infusion pump.
It is a further object of the present invention to provide a disposable tube set which is visually and tactilely keyed to directional fluid flow and flow rate in a mutually keyed receiver of a peristaltic infusion pump system.